updating a remote copy of SVN

Hi,

I would like to know if it is possible to ssh tunnel or somehow update a
remote copy of my subversion tree. I've checked the FAQ and I know that
you can just start up an remote shell on the machine, but the problem I
have is a bit more complex

I have three machines:

A - which maintains the a remote subversion tree
B - A cluster where I would like to do some development but cannot see A
C - A machine which can see both A & B

How can I use C to update the subversion archive on B from A?

Make sense?
Possible?

Firewalls stink!

Thanks,

-- Pete

-- 
Pete Schuck
peter.schuck_at_nasa.gov
Room 250, Building 21
Space Weather Laboratory, Code 674
Heliophysics Science Division
NASA Goddard Space Flight Center
8800 Greenbelt Rd.
Greenbelt, MD 20771
Work: (301) 286-3008
Cell: (240) 393-9607
 fax: (301) 286-5348   
-----------------------------------------------------
Nullius in verba
For the materialist, science is what teaches us what to believe. For
the empiricist, science is more nearly what teaches us how to give up
our beliefs.  ---  Bas van Fraassen
Because the truth is important --- Jordan Schuck (Age 7)